Pathogenic parasites in ready-to-eat salads and berries sold on the Italian market

Among fresh produce, in recent years, the consumption of ready-to-eat (RTE) salads and berries has significantly increased in industrialized countries due to a trend towards faster and healthier eating habits. These products can be contaminated along the production food chain by several microorganisms, including pathogenic parasites that have been responsible of foodborne outbreaks worldwide. In Italy, while data on contamination of RTE salads require more-in-depth investigations there is a complete lack of data on berries, mostly imported from countries where some of these parasitic infections are endemic. The aim of this Ph.D. project was to investigate the occurrence of foodborne parasites as contaminants of imported and locally produced fresh produce sold on the Italian market. From January to December 2019, 648 packages of three brands of RTE mixed salads and three berry-types were bought from supermarkets. To estimate the prevalence, for each fresh produce, a pool size of nine packages each month and 72 pools per one year were processed. After washing, the pellets were examined by microscopy (FLOTAC) and subjected to different molecular techniques (conventional PCR, simplex or multiplex qPCR) and sequencing. By microscopy, Cyclospora-like oocysts and a taeniid egg were detected in a blueberry sample and in a RTE salad sample, respectively; Entamoeba and Giardia were also identified. Cyclospora cayetanensis and Entamoeba histolytica in imported blueberries and the Taeniid (Echinococcus multilocularis) in locally produced RTE salads were molecularly confirmed. Cryptosporidium ryanae, Cryptosporidium bovis, Cryptosporidium xiaoi and Cryptosporidium ubiquitum and Giardia duodenalis Assemblages A, B and E, most of them of zoonotic interest, were identified in both matrices. The overall prevalence of each parasite was 5.81% for Cryptosporidium spp., 4.63% for G. duodenalis, 0.15% for C. cayetanensis, 0.15% for E. multilocularis. Entamoeba spp. was also detected with a prevalence of 0.96%. Toxoplasma gondii was not found. Cryptosporidium spp. and G. duodenalis showed significant seasonal differences with higher values in winter and spring, respectively. In this study, most of the parasite species were detected for the first time on fresh produce. The results obtained, beside opening a new epidemiological scenario in Italy, highlight the improper management of fresh produce, both locally produced or imported, along the food chain and the potential consequences of such contamination on human health.